The distance between point P and point Q is (D2 - 15) km. Boat X completes a round trip from point P to Q and back in (D - 1) hours. Given that the downstream and upstream speeds of Boat X are 60 km/h and 20 km/h respectively, the value of D is what percent of the upstream distance of 180 km traveled by Boat T?

P takes 6 hours more than Q to walk 'm' km. If P doubles his speed, then he can make it in 2 hours less than Q. How much time (in hours) does P require to walk 'm' km?

A policeman spots a thief from a distance of 105 metres. The thief and the policeman travel at speeds of 90 km/h and 100 km/h respectively. How long will it take the policeman to catch the thief?